The present invention relates to a method and apparatus for correcting errors in PCM signals which are recorded by a plurality of heads on time succession overlapping tracks by a plurality of rotating heads.
The following ways are known to record PCM signals on recorders employing rotating heads:
1. by way of PCM adapters for videorecorders: a PCM audio signal is here converted to a video signal and is recorded in the same manner as a video signal (FIG. 3).
2. by recording a PCM audio signal intended for a standard 8 mm video recording on an extension of the track produced by enlarging the head wheel loop angle (IEEE Transactions and Consumer Electronics, Vol. CE-28, No. 3, August, 1982, pages 241-249);
3. by recording a PCM video signal wherein each recording track is provided with a data block, which does not contain important data, so that the switching of heads can take place in that block (Professional Video, October, 1982, pages 10, 12).
Thus, no case involves continuous PCM signals, as they are scanned, for example, from a compact disc (CD) or are broadcast in PCM radio. To be able to record these continuous signals according to one of the conventional PCM recording methods, e.g. on a video recorder, they must first be converted, by time compression, into a signal which includes a time gap in which the switching of heads can take place during playback.
Up till now, there does not exist a way to play back without errors a PCM signal that has been recorded without special provisions for the switching of heads. In such case it would no longer be necessary for the PCM signal and the head wheel rotation to be coupled. This may be of advantage, for example, if a PCM audio signal is to be recorded simultaneously with a video signal and the PCM signal comes from a source which is not coupled with the video signal. Since the head wheel rotation must be coupled with the video signal, no coupling can then exist between the head wheel rotation and the PCM signal.